Light source device

ABSTRACT

A light source device includes a substrate and a light source. The light source includes a first light emission unit, a plurality of second light emission units, and a plurality of third light emission units arranged two-dimensionally on the substrate. The first light emission unit is arranged at a center among the light emission units, and includes a first light emission element having a first light emission face. The second light emission units surround the first light emission unit, and include a plurality of second light emission elements, respectively, each having a second light emission face. The third light emission units surround the second light emission units, and include a plurality of third light emission elements, respectively, each having a third light emission faces. The first light emission face and the second light emission faces all have the same areas. The third light emission faces have different areas.

CROSS-REFERENCE TO RELATED APPLICATION

This is a continuation application of U.S. application Ser. No.18/062,514, filed on Dec. 6, 2022, which is a continuation applicationof U.S. application Ser. No. 17/537,467, filed on Nov. 29, 2021, nowU.S. Pat. No. 11,563,145. This application claims priority to JapanesePatent Application No. 2020-198840, filed on Nov. 30, 2020. The entiredisclosures of U.S. application Ser. Nos. 18/062,514 and 17/537,467, andJapanese Patent Application No. 2020-198840 are hereby incorporatedherein by reference.

BACKGROUND

The present disclosure relates to a light source, a light source device,and a method of manufacturing a light source.

Light sources having a plurality of light emitting elements arranged inan array are utilized in a wide range of application areas. Driving agiven portion of the plurality of light emitting elements allows suchlight sources to perform partial irradiation to change the irradiatedarea. Such characteristics can be utilized to produce a lighting devicehaving features that were unavailable in the past. For example, JapanesePatent Publication No. 2016-219637 discloses a light source applicableto an automotive adaptive front-lighting system.

SUMMARY

The present disclosure provides a light source having good emissioncharacteristics during partial irradiation, such a light source device,and a method of manufacturing the light source.

A light source device according to an embodiment of the presentdisclosure includes a substrate and a light source. The light sourceincludes a plurality of light emission units arranged two-dimensionallyon the substrate. The light emission units include a first lightemission unit, a plurality of second light emission units, and aplurality of third light emission units. The first light emission unitis arranged at a center among the light emission units. The firstemission unit includes a first light emission element having a firstlight emission face. The second light emission units surround the firstlight emission unit. The second light emission units include a pluralityof second light emission elements, respectively. The second lightemission elements have a plurality of second light emission faces,respectively. The third light emission units surround the second lightemission units. The third light emission units include a plurality ofthird light emission elements, respectively. The third light emissionelements have a plurality of third light emission faces, respectively.The first light emission face and the second light emission faces allhave the same areas. The third light emission faces have differentareas.

A light source device according to an embodiment of the presentdisclosure includes a lens mounted at a predetermined distance from thelight source.

According to certain embodiments of the present disclosure, a lightsource having good emission characteristics during partial irradiation,and such a light source device can be provided.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic perspective view of a light source according to afirst embodiment.

FIG. 2A is a schematic top view of the light source shown in FIG. 1 .

FIG. 2B is a schematic cross-sectional view of the light source takenalong line 2B-2B in FIG. 2A.

FIG. 2C is a schematic cross-sectional view of a light emission unit.

FIG. 2D is a schematic top view of the light emission unit.

FIG. 3 is a flowchart showing a method of manufacturing the light sourceaccording to the first embodiment.

FIG. 4A is a cross-sectional view showing a process in the method ofmanufacturing the light source according to the first embodiment.

FIG. 4B is a cross-sectional view showing a process in the method ofmanufacturing the light source according to the first embodiment.

FIG. 4C is a cross-sectional view showing a process in the method ofmanufacturing the light source according to the first embodiment.

FIG. 4D is a cross-sectional view showing a process in the method ofmanufacturing the light source according to the first embodiment.

FIG. 4E is a cross-sectional view showing a process in the method ofmanufacturing the light source according to the first embodiment.

FIG. 4F is a cross-sectional view showing a process in the method ofmanufacturing the light source according to the first embodiment.

FIG. 4G is a cross-sectional view showing a process in the method ofmanufacturing the light source according to the first embodiment.

FIG. 5A is a schematic cross-sectional view of the tip of a blade usedto form a first or second groove.

FIG. 5B is a schematic cross-sectional view of the tip of a blade usedto form a first or second groove.

FIG. 5C is a schematic cross-sectional view of the tip of a blade usedto form a first or second groove.

FIG. 6A is a schematic cross-sectional view of another form of a lightemission unit.

FIG. 6B is a schematic cross-sectional view of another form of a lightemission unit.

FIG. 7A is a schematic cross-sectional view of another form of a lightsource.

FIG. 7B is a schematic cross-sectional view of a light emission unit inthe light source shown in FIG. 7A.

FIG. 7C is a schematic cross-sectional view of another form of a lightemission unit.

FIG. 8A is a schematic cross-sectional view of a light source accordingto a second embodiment.

FIG. 8B is a schematic cross-sectional view of a light emission unitaccording to the second embodiment.

FIG. 9A is a schematic cross-sectional view showing a process in amethod of manufacturing the light source according to the secondembodiment.

FIG. 9B is the schematic cross-sectional view showing a process in themethod of manufacturing a light source according to the secondembodiment.

FIG. 10A is a schematic cross-sectional view of another form of a lightemission unit.

FIG. 10B is a schematic cross-sectional view of another form of a lightemission unit.

FIG. 10C is a schematic cross-sectional view of another form of a lightemission unit.

FIG. 11 is a schematic top view of a light source according to a thirdembodiment.

FIG. 12A is a schematic top view of a light source device according to afourth embodiment.

FIG. 12B is a schematic cross-sectional view of the light source devicetaken along line 12B-12B in FIG. 12A.

FIG. 13A shows a simulation result of the luminance distribution of thelight source of a test example.

FIG. 13B shows a simulation result of the luminance distribution of thelight source of a comparative example.

DETAILED DESCRIPTION

Certain embodiments of the present disclosure will be explained indetail below with reference to the accompanying drawings. Theembodiments described below are exemplary, and the light sources, lightsource device, and the methods of manufacturing the light sourcesaccording to the present disclosure are not limited to those describedbelow. For example, the numerical values, shapes, materials,manufacturing steps, and the sequence of the steps described in theembodiments described below are merely examples, and are modifiable invarious ways to the extent that such a modification does not causetechnical inconsistencies. Each of the embodiments described below ismerely exemplary, and various combinations can be made to the extentthat such a combination does not cause technical inconsistencies.

The sizes, shapes, and the like of the constituent elements shown in thedrawings might be exaggerated for clarity of explanation, and might notreflect the sizes and shapes of, and the relative sizes among theconstituent elements in an actual light source. Certain elements mightbe omitted in a drawing or only a cut end face might be used as across-sectional view so as not to make the drawing excessively complex.

In the description below, the constituent elements having practicallythe same functions are denoted by common reference numerals for whichexplanation might be omitted. In the description below, terms indicatingspecific directions or positions (e.g., “upper,” “lower,” “right,”“left” and other terms including or related to these) might be used.These terms, however, are merely used in order to make the relativedirections or positions in the drawings being referenced more easilyunderstood. As long as the relationship between relative directions orpositions indicated with the terms such as “upper,” “lower,” or the likeis the same as those in a referenced drawing, the layout of the elementsin other drawings, or actual products and manufacturing equipmentoutside of the present disclosure, does not have to be the same as thoseshown in the referenced drawing. In the present disclosure, being“parallel” includes cases where two straight lines, sides, planes, orthe like, form an angle in the range of 0° to about ±5° unless otherwisespecifically stated.

In the present disclosure, being “perpendicular” or “orthogonal”includes cases where two straight lines, sides, planes, or the like forman angle in the range of from 90° to about ±5° unless otherwisespecifically stated. Furthermore, the positional relationships ofconstituent elements expressed with the term “upper” include cases inwhich a constituent element is in contact with another, as well as casesin which a constituent element is positioned above another without beingin contact.

The drawings referenced below include arrows indicating the x, y, and zaxes that are orthogonal to one another. The x direction along the xaxis represents a predetermined direction in the plane where the lightemission units of the light source according to each embodiment arearranged, i.e., the light emission unit arrangement plane, the directionalong the y axis is the direction orthogonal to the x direction in thelight emission unit arrangement plane, and the z direction along the zaxis is the direction orthogonal to the arrangement plane. The xdirection pointed by the arrow represents the +x direction, and thedirection opposite the +x direction represents the −x direction. The ydirection pointed by the arrow represents the +y direction, and thedirection opposite the +y direction represents the −y direction. The zdirection pointed by the arrow represents the +z direction, and thedirection opposite the +z direction represents the −z direction. In eachembodiment, the light source, as an example, outputs light in the +zdirection. This, however, is not intended to restrict the orientation ofthe light source or the light source device in use, and the light sourceand the light source device can be oriented in any way.

First Embodiment Structure of Light Source 101

FIG. 1 is a schematic perspective view of a light source 101 accordingto a first embodiment, FIG. 2A is a schematic top view of the lightsource 101, and FIG. 2B is a schematic cross-sectional view of the lightsource 101 taken along line 2B-2B in FIG. 2A. The light source 101includes a plurality of light emission units 51 and a light shieldingmember 60.

The light emission units 51 are one- or two-dimensionally arranged. Asused herein, the light emission units 51 are one-dimensionally arrangedwhen all the light emission units 51 are aligned along a single row orcolumn, while the light emission units 51 are two-dimensionally arrangedwhen the light emission units 51 are arranged in rows and columns. Forexample, as shown in FIG. 2 , the light emission units 51 aretwo-dimensionally arranged in the x direction and the y direction. Inthis embodiment, the light source 101 includes 63 light emission units51 arranged in the x and y directions, 7 rows by 9 columns. The numberof light emission units 51 to be included in the light source 101 isoptional, and can be any other number, for example, about 9 to about 400units arranged 3 rows by 3 columns to 20 rows by 20 columns.

A light emission unit 51 has, for example, a square or rectangular shapein a top view, i.e., in the x-y plane, each side being 100 μm to 500 μm,preferably 200 μm to 400 μm. The light source 101 has, for example, asquare or rectangular shape in the x-y plane, each side being 1 mm to 5mm, preferably 2 mm to 3 mm. The light source 101 is about 100 μm toabout 1 mm in thickness, for example. The size and the number of lightemission units 51, and the size of the light source 101 can bedetermined in accordance with the application. For example, the lightsource 101 can be used as a photographic flash or video lighting ofportable devices such as a smartphone or the like.

FIG. 2C is a schematic cross-sectional view of a light emission unit 51.FIG. 2D is a schematic top view of the light emission unit 51. Eachlight emission unit 51 includes a light emitting element 20 having alight emission face 20 a, a wavelength conversion member 30 disposed onthe light emission face 20 a, and a light transmissive member 40disposed on the upper face 30 a of the wavelength conversion member 30.In this embodiment, the light emission faces 20 a of the light emittingelements 20 are equal in size. A light shielding member 60 is providedcontinuously between the light emission units 51 to cover the lateralfaces 20 c of the light emitting elements 20 and the lateral faces 30 cof the wavelength conversion members 30. At least a part of the lateralfaces of the light transmissive member of each light emission unit isexposed from the light shielding member 60. The structure of a lightemission unit 51 will be explained in more detail element by element.

Light Emitting Element 20

A light emitting element 20 has a light emission face 20 a, an electrodeface 20 b and lateral faces 20 c. On the electrode face 20 b, positiveand negative electrodes 21 are positioned.

The light emitting element 20 is a semiconductor light emitting element,such as a laser diode (LD), light emitting diode (LED), or the like. Thelight emitting element 20 is typically a LED. The light emitting element20 includes, for example, a sapphire or gallium nitride supportsubstrate, and a semiconductor stacked body on the support substrate.The semiconductor stacked body includes an n-type semiconductor layer, ap-type semiconductor layer, an active layer interposed between these twolayers, and p-side and n-side electrodes electrically connected to then-type and p-type semiconductor layers. The semiconductor stacked bodymay include a nitride semiconductor (In_(x)Al_(y)Ga_(1-x-y)N, 0≤x, 0≤y,x+y≤1) capable of emitting light in the ultraviolet to visible spectra.The positive and negative electrodes 21 are electrically connected tothe p-side and the n-side electrodes.

The light emitting element 20 may be a blue light emitting element, or alight emitting element emitting light of another color, such as red,green, or ultraviolet. In this embodiment, a blue light emitting LED isillustrated as the light emitting element 20 in each light emission unit51.

The shape of the upper face, the light emission face 20 a, of a lightemitting element 20 is typically quadrangular. The length of a side ofthe quadrangular light emission face 20 a is preferably smaller than thelength of the corresponding side of the light emission unit 51 in a topview. For example, the length of a side of the quadrangular lightemitting element 20 is 50 μm to 300 μm.

Wavelength Conversion Member 30

A wavelength conversion member 30 is disposed on the light emission face20 a of each light emitting element 20. The wavelength conversion member30 absorbs a portion of the light exiting the light emission face 20 aof the light emitting element 20 and emits light having a longerwavelength than that of the absorbed light.

In a top view, the wavelength conversion member 30 is preferably largerthan the light emission face 20 a of the light emitting element 20. Thisallows a larger area than the light emission face 20 a of the lightemitting element 20 to output wavelength-converted light (e.g., whitelight). This can reduce the generation of low luminance regions betweenthe light emission units 51 when multiple light emission units 51 arelit, even in the case in which the light emitting elements 20 cannot bearranged at sufficiently small intervals in the light source 101.

Each wavelength conversion member 30 includes, for example, a lighttransmissive resin and a phosphor. For the phosphor, for example,yttrium aluminum garnet based phosphors (e.g., Y₃(Al,Ga)₅O₁₂:Ce),lutetium aluminum garnet based phosphors (e.g., Lu₃(Al,Ga)₅O₁₂:Ce),terbium aluminum garnet based phosphors (e.g., Tb₃(Al,Ga)₅O₁₂:Ce),β-SiAlON phosphors (e.g., Si,Al)₃(ON)₄:Eu), α-SiAlON phosphors (e.g.,M_(z)(Si,Al)₁₂(O,N)₁₆ (0<z≤2, and M is Li, Mg, Ca, Y, and lanthanideelements excluding La and Ce), nitride based phosphors, such asCASN-based phosphors (e.g., CaAlSiN₃:Eu) or SCASN based phosphors (e.g.,(Sr,Ca)AlSiN₃:Eu), fluoride based phosphors, such as KSF based phosphors(e.g., K₂SiF₆:Mn) or MGF based phosphors (e.g., 3.5MgO·0.5MgF₂·GeO₂:Mn),perovskite, chalcopyrite, or quantum dot phosphors can be used.

For the light transmissive resin, a silicone resin, modified siliconeresin, epoxy resin, modified epoxy resin, acrylic resin, or fluorineresin can be used. A blend of these resins may alternatively be used.

The wavelength conversion member 30 may include several types ofphosphors, for example, a phosphor that absorbs blue light and emitsyellow light and a phosphor that absorbs blue light and emits red light.This allows the light emission unit 51 to emit desired white light.

The wavelength conversion members 30 may contain a light diffusingmaterial to the extent that it does not block light. The light diffusingmaterial content in the wavelength conversion members 30 can be adjustedsuch that the transmittance of the wavelength conversion members 30 withrespect to the light exiting the light emitting elements 20 and/or thewavelength-converted light is 50% to 99%, preferably 70% to 90%. For thelight diffusing material, for example, titanium oxide, silicon oxide,aluminum oxide, zinc oxide, or glass can be used.

For the wavelength conversion members 30, glass containing a phosphormay be used. Alternatively, the wavelength conversion members may be asintered body composed only of a phosphor, or a sintered body whichincludes a phosphor and any of the light diffusing materials describedabove.

Light Transmissive Member 40

A light transmissive member 40 is provided on the upper face 30 a ofeach wavelength conversion member 30, covering the upper face 30 a. Thelight transmissive member 40 constitutes the light emission face of alight emission unit 51. The light transmissive member 40 can reduce theluminance nonuniformity of the light exiting the wavelength conversionmember 30.

Each light transmissive member 40 has an upper face 40 a and a lowerface located opposite to the upper face 40 a. The light transmissivemember 40, when the upper face 40 a is viewed from above, has a firstregion R1 positioned above a light emitting element 20, and a secondregion R2 positioned outward from the first region R1. In thisembodiment, the area of the first region R1 is larger than the area ofthe light emission face 20 a of the light emitting element 20, but thearea of the first region R1 may be the same as the area of the lightemission face 20 a. In FIG. 2D, for the sake of clarity, no hatching isapplied to the first region R1, but the same hatching patterns as thosein FIG. 2C are applied to the second region R2 and the light shieldingmember 60. As shown in FIG. 2D, the second region R2 surrounds the firstregion R1.

In each light transmissive member 40, the first region R1 is larger inthickness than the second region. In other words, the thickness t2 ofthe second region R2 is smaller than the thickness t1 of the firstregion R1. In this embodiment, a recessed portion 40 r (i.e., secondgroove 162 described later) is created in the peripheral portion of eachlight transmissive member 40 in the upper face of the light source 101,whereby a second region R2 is formed in each light transmissive member40. The creation of a recessed portion 40 r makes the area of the upperface 40 a smaller than the lower face 40 b.

Each light transmissive member 40 has lateral faces positioned betweenthe upper face 40 a and the lower face 40 b. The lateral faces each havea first lateral face 40 c 1 and a second lateral face 40 c 2 in theheight direction of the light transmissive member 40. The first lateralface 40 c 1 and the second lateral face 40 c 2 are defined by therecessed portion 40 r. Each light transmissive member 40 may have anintermediary face 40 d between the first lateral face 40 c 1 and thesecond lateral face 40 c 2 which is substantially parallel to the upperface 40 a and the lower face 40 b.

The first lateral face 40 c 1 is the lateral face of the recessedportion 40 r, and is contiguous with the upper face 40 a. The secondlateral face 40 c 2 is contiguous with the lower face 40 b. Theintermediary face 40 d is the bottom face of the recessed portion 40 r.As described later, the first lateral face 40 c 1 is exposed from thelight shielding member 60, but the second lateral faces 40 c 2 arecovered by the light shielding member 60. In other words, each lighttransmissive member 40 is constructed such that the recessed portion 40r created exposes at least some portions of the lateral faces from thelight shielding member 60.

The light transmissive members 40 can be constructed by using a similarresin to the light transmissive resin used for the wavelength conversionmembers 30. The light transmissive members 40 can be formed of glass ora ceramic having light transmissivity.

The light transmissive members 40 preferably contain a light diffusingmaterial. For the light diffusing material, the same or a similarmaterial to the light diffusing material that can be added to thewavelength conversion members 30 can be used.

Light Shielding Member 60

A light shielding member 60 is continuously disposed between the lightemission units 51 while covering the lateral faces 20 c of the lightemitting elements 20 and the lateral faces 30 c of the wavelengthconversion members 30 in each light emission unit 51. The lightshielding member 60 has light shielding properties or lightreflectivity. By covering at least these lateral faces, the lightshielding member 60 can hinder the light exiting the lateral faces 20 cof the light emitting element 20 and the lateral faces 30 c of thewavelength conversion member 30 in each light emission unit 51 fromentering any adjacent light emission unit 51.

In this embodiment, the light shielding member 60 extends from thelateral faces of the light emitting elements 20 to cover the electrodefaces 20 b of the light emitting elements 20. However, the surfaces ofthe electrodes 21 on the electrode faces 20 b are exposed from the lightshielding member 60. Because the wavelength conversion members 30 arelarger than the light emission faces 20 a of the light emitting elements20, the areas of the lower faces 30 b not in contact with the lightemission faces 20 a are covered by the light shielding member 60. Thelight shielding member 60 also covers the second lateral faces 40 c 2 ofthe light transmissive members 40.

The reflectance of the light shielding member 60 is preferably 20% to95%, for example, more preferably 50% to 95%. The light shielding member60, for example, includes a light diffusing material and a resinmaterial. For the resin material and the light diffusing material, alight transmissive resin and a light diffusing material similar to thoseused for the wavelength conversion members 30 can be used. The lightshielding member may contain a light absorbing material such as carbonblack in addition to the light diffusing material.

Operation of Light Source 101

In a light source 101, the light exiting the light emission faces 20 aof the light emitting elements 20 passes through the wavelengthconversion members 30 and the light transmissive members 40 beforeexiting the light source. At this time, the wavelength of at least aportion of the light from the light emitting elements 20 is converted bythe wavelength conversion members 30. The light externally outputincludes the light which has exited the light emitting elements 20 andthe wavelength-converted light. For example, in the case in which thelight emitting elements 20 emit blue light and the wavelength conversionmembers 30 contain at least a yellow-emitting phosphor, the light source101 emits white light resulting from mixing the blue light and theyellow light.

The light source 101 structured as above has good emissioncharacteristics during partial irradiation. Specifically, because thewavelength conversion members 30 are larger than the light emissionfaces 20 a of the light emitting elements 20 in a top view, the lightsource can output white light through larger areas than the lightemission faces 20 a of the light emitting elements 20. This can reducethe generation of low luminance regions between the light emission units51 when multiple light emission units 51 are lit, even in the case inwhich the light emitting elements 20 cannot be arranged at sufficientlysmall intervals.

Furthermore, the distance between the wavelength conversion members 30in two adjacent light emission units 51 is smaller than the distancebetween the corresponding light emitting elements 20. In the lightsource 101, a light shielding member 60 is disposed between the facinglateral faces of the light emitting elements 20 and the facing lateralfaces 30 c of the wavelength conversion members 30 of adjacent lightemission units 51. This can hinder the light from the light emittingelement 20 in each light emission unit 51 from entering the wavelengthconversion members 30 of any adjacent light emission unit 51, as well asreducing the propagation of light between adjacent wavelength conversionmembers 30. This can reduce the leakage of light along the boundarybetween a lit light emission unit 51 and an unlit light emission unit51.

Each light transmissive member 40 includes a first region R1 positionedabove the light emitting element 20 and a second region R2 located onthe outside of the first region R1. In each light transmissive member40, as compared to the first region R1 located immediately above thelight emitting element 20 in which the luminance is relatively high, asmaller thickness is given to the second region R2 located in theperiphery of the first region R1 and having low luminance. Accordingly,allowing the light transmissive members 40 to contain a light diffusingmaterial can reduce the absorption and diffusion of light by the secondregion R2 as compared to the first region R1 of each light transmissivemember 40, thereby enhancing the luminance uniformity of the lightexiting the light transmissive members 40.

The light transmissive members 40 have the first lateral faces 40 c 1that are not covered by the light shielding member 60. In other words,between two adjacent light emission units 51 in the light source 101,the first lateral faces 40 c 1 of the light transmissive members 40 faceone another without interposing a light shielding member 60. This allowsthe light to laterally exit the first lateral faces 40 c 1 of the lighttransmissive members 40, thereby lessening the luminance decline alongthe boundary between two adjacent light emission units 51. This canreduce the generation of a dark line between two adjacent light emissionunits 51 when both are lit.

Method of Manufacturing Light Source 101

One embodiment of a method of manufacturing a light source 101 will beexplained. FIG. 3 is a flowchart of an example of a method ofmanufacturing a light source 101, and FIGS. 4A to 4K are cross-sectionalviews each showing a process in the method of manufacturing a lightsource 101 shown in FIG. 3 . The method of manufacturing a light source101 according to this embodiment includes at least, a light emittingelement bonding step (S1), a first groove forming step (S2), a lightshielding member disposing step (S3), and a second groove forming step(S4).

Light Emitting Element Bonding Step (S1)

As shown in FIG. 4A, a light transmissive layer 140 which is amonolithic body of light transmissive members and a wavelengthconversion layer 130 which is a monolithic body of wavelength conversionmembers are adhered by using an adhesive or an adhesive sheet to obtaina stacked body 150. The light transmissive layer 140 and the wavelengthconversion layer 130 may have the size that corresponds to a lightsource 101, or a size for producing multiple light sources 101. Thelight transmissive layer 140 of the stacked body 150 is temporalityfixed to a support 120.

As shown in FIG. 4B, a plurality of light emitting elements 20 arebonded to the stacked body 150. The light emitting elements 120 arearranged and bonded to the wavelength conversion layer 130 whileallowing the light emission faces 20 a of the light emitting elements 20to face the wavelength conversion layer 130. By disposing an adhesive oradhesive sheet on the surface of the wavelength conversion layer 130 orthe light emission faces 20 a of the light emitting elements 20 inadvance, the light emitting elements 20 can be bonded to the wavelengthconversion layer 130 via the adhesive material. The light emittingelements 20 are one- or two-dimensionally arranged using the pitch usedfor the light emission units 51 in the light source 101.

The bonding between the light transmissive layer 140 and the wavelengthconversion layer 130, and between the wavelength conversion layer 130and the light emitting elements 20 may be done directly withoutinterposing any adhesive material by utilizing the tackiness of thelight transmissive layer 140 and the wavelength conversion layer 130.

First Groove Forming Step (S2)

As shown in FIG. 4C, first grooves 161 which segmentize the stacked body150 are formed between adjacent light emitting elements 20. By applyinga dicing saw blade or the like at the positions of the stacked body 150indicated by the arrows in FIG. 4B, the first grooves 161 as shown inFIG. 4C having a width w1 are formed in the stacked body 150 by cuttingfrom the wavelength conversion layer 130 side. This provides each lightemitting element 20 with a wavelength conversion member 30 and a lighttransmissive member 40. The lateral faces 30 c of the wavelengthconversion members 30 and the lateral faces 40 c of the lighttransmissive members 40 are exposed at the lateral faces defining thefirst grooves 161.

In this process, the first grooves 161 do not have to completelysegmentalize the stacked body 150. It is sufficient for the firstgrooves to completely segmentalize at least the wavelength conversionlayer 130 and reach the light transmissive layer 140. The lighttransmissive layer 140 may be partially removed or not removed at all bythe first grooves 161.

Light Shielding Member Disposing Step (S3)

As shown in FIG. 4D, a light shielding member 60 is disposed between thelight emitting elements 20. Specifically, the light shielding member 60is disposed to cover the lateral faces 30 c of the wavelength conversionmembers 30 and the lateral faces 40 c of the light transmissive members40 exposed at the lateral faces defining the first grooves 161 and thelateral faces 20 c of the light emitting elements 20. In thisembodiment, the light shielding member 60 is disposed to cover theelectrode faces 20 b and the electrodes 21 on the electrode face 20 b ofthe light emitting elements 20. The light shielding member 60 can beformed, for example, by transfer molding, potting, printing, spraying,or the like.

As shown in FIG. 4E, the surfaces of the electrodes 21 of the lightemitting elements 20 are exposed by grinding or cutting off a portion ofthe light shielding member 60 from the upper face 60 b.

Second Groove Forming Step (S4)

As shown in FIG. 4F, the support 120 is removed from the lighttransmissive members 40 to expose the upper faces 40 a of the lighttransmissive members 40 located opposite to the faces in contact withthe wavelength conversion members 30. As shown in FIG. 4G, secondgrooves 162 that expose some portions of the lateral faces of the lighttransmissive members 40 from the light shielding member 60 are formed byremoving from the upper face 40 a side the outer edge portions of thelight shielding member 60 located between the light transmissive members40. The second grooves 162 can be formed by using a blade, such as adicing saw.

In this embodiment, because the second grooves 162 each have a largerwidth w2 than the width w1 of the first grooves 161, the outer edgeportions of the light transmissive members 40 facing one another via thelight shielding member 60 are also made absent by the second grooves162. The second grooves 162 which do not reach the wavelength conversionmembers 30 have a depth of about one half of the thickness of the lighttransmissive members 40. In the case in which the stacked body 150 isnot completely segmentalized by the first grooves 161 formed during thefirst groove forming step, the second grooves 162 are formed to thedepth to reach the first grooves 161.

The cross-sectional shape of a second groove 162 reflects thecross-sectional shape of the blade used to form the second groove 162.In this embodiment, the tip of a blade having a rectangularcross-sectional shape as shown in FIG. 5A forms the first lateral faces40 c 1 that are perpendicular to the upper faces 40 a. Forming thesecond grooves 162 provides the light transmissive members 40 with thefirst lateral faces 40 c 1 exposed from the light shielding member 60and the second lateral faces 40 c 2 covered by the light shieldingmember 60.

The light source 101 is completed in this manner. In the case in whichthe light transmissive layer 140 and the wavelength conversion layer 130have the size that corresponds to multiple light sources 101, themultiple light sources 101 are linked by the light shielding member 60.Accordingly, the light sources 101 are completed after cutting the lightshielding member 60 along the boundaries of the light sources 101.

Other Forms

Various modifications can be made to the light source according to thepresent disclosure. As described above, the shape of the first lateralfaces of the light transmissive member 40 of each light emission unit 51can be changed by using a blade having a different tip in forming thesecond grooves 162.

In the case of forming the second grooves 162 using a blade having a tipthat has a U-shaped or curved line cross section as shown in FIG. 5B,the first lateral faces 40 c 1 of a light transmissive member 40 eachhave a curved portion as shown in FIG. 6A. The second lateral faces 40 c2, similar to FIG. 2C, are planar because the second lateral faces 40 c2 are formed by the first grooves 161.

In the case of forming the second grooves 162 using a blade having a tipthat has a trapezoidal cross section as shown in FIG. 5C, the firstlateral faces 40 c 1 of the light transmissive member 40 are oblique tothe vertical direction as shown in FIG. 6B.

As described above, the direction of the light exiting the first lateralfaces 40 c 1 can be altered by changing the shape or the inclination ofthe first lateral faces 40 c 1. This can adjust the distribution of thelight laterally exiting the light emission units 51.

FIGS. 7A and 7B show an example of a light source 102 having lighttransmissive members in another form. As shown in FIGS. 7A and 7B, thelight source 102 differs from the light source 101 shown in FIGS. 2A and2B in that each light emission unit 52 has a light transmissive memberthat has no second lateral faces. In each light emission unit 52 of thelight source 102, the first lateral faces 41 c 1 of the lighttransmissive member 42 are contiguous with the upper face 40 a and thelower face 40 b without any second lateral face. In other words, thelateral faces of the light transmissive member 42 of each light emissionunit 52 of the light source 102 are entirely exposed from the lightshielding member 60. The first lateral faces 42 c 1 each have a curvedface portion. The light source 102 including the light transmissivemembers 42 with such a shape can be produced by forming second grooves162 that reach the wavelength conversion members 30 by using a bladehaving the cross-sectional shape shown in FIG. 5B. Similarly, a lightsource 103 including the light transmissive member 43 shown in FIG. 7Ccan be produced by forming second grooves 162 that reach the wavelengthconversion member 30 using a blade having the cross-sectional shapeshown in FIG. 5C. The light transmissive member 43 has planar firstlateral faces 43 c 1 oblique to the vertical direction.

Second Embodiment

FIG. 8A is a schematic cross-sectional view of a light source 104according to a second embodiment, and FIG. 8B is a schematiccross-sectional view of a light emission unit 54. The light source 104differs from the light source 101 of the first embodiment such that thearea of the upper face 44 a is larger than the lower face 44 b of thelight transmissive member 44 in each light emission unit 54. Similar tothe first embodiment, the thickness of the second region R2 is smallerthan the first region R1 in the light transmissive member 44. The firstlateral faces 44 c 1 are exposed from the light shielding member 60, andthe second lateral faces 44 c 2 are covered by the light shieldingmember 60. The light source 104 exhibits a similar effect to thatachieved by the first embodiment.

The light source 104 can be manufactured by modifying the steps offorming the first grooves 161 and the second groves 162 in the method ofmanufacturing a light source according to the first embodiment.Specifically, as shown in FIG. 9A, first grooves 171 that reach thelight transmissive layer 140 are formed by segmentalizing the wavelengthconversion layer 130 between the light emitting elements 20 from thewavelength conversion layer 130 side. The width w1 of the first grooves171 is set larger than the width w1 of the first grooves 161 of thefirst embodiment. The first grooves 171 are formed so as not to reachthe support 120. In other words, the light transmissive layer 140 is notsegmentalized by the first grooves 171. Forming the first grooves 171segmentalizes the wavelength conversion layer 130, providing each lightemission unit 54 with a wavelength conversion member 30. A lightshielding member 60 is disposed in the first grooves 171.

Then second grooves that reach the light shielding member 60 are formedby partially removing the light transmissive layer 140 located betweenthe light emitting elements from the light transmissive layer 140 side.This provides light transmissive members 40 respectively positioned onthe wavelength conversion members 30. When forming the second grooves172, as shown in FIG. 9B, the width w2 of the second grooves 172 ispreferably set smaller than the width w1 of the first grooves 171. Inthis embodiment, the depth of the second grooves 172 is set to cut thelight transmissive layer 140 and reach the first grooves 171. By formingthe second grooves 172, the light transmissive layer 140 issegmentalized to form light transmissive members 44 respectivelycorresponding to the light emission units 54.

Other Forms

Similar to the first embodiment, by changing the shape of the blade usedwhen forming the first grooves 171, the shape of the second lateralfaces of the light transmissive member 44 in each light emission unit 54can be changed.

In the case of forming the first grooves 171 by using a blade having acurved edge in a cross section shown in FIG. 5B, the second lateralfaces 40 c 2 of the light transmissive member 44 each include a curvedface portion as shown in FIG. 10A.

In the case of forming the first grooves 171 by using a blade having atrapezoidal cross section shown in FIG. 5C, the second lateral faces 40c 2 of the light transmissive member 44 are oblique to the verticaldirection as shown in FIG. 10B.

Forming the first grooves 171 by using a blade having the same shape asthat of the blade for forming the second grooves 172 and making thewidth w1 of the first grooves 171 the same as the width of the secondgrooves 172 can produce a light source 105 which includes light emissionunits 55 each equipped with the light transmissive member 45 in the formshown in FIG. 10C. The light source 105 differs from the light source101 of the first embodiment such that the area of the upper face 45 aand the area of the lower face 45 b of the light transmissive member 45are equal in each light emission unit 55. Each light transmissive member45 has lateral faces 45 c contiguous with the upper face 45 a and thelower face 45 b in which a portion of each lateral face 45 c on theupper face 45 a side is exposed from the light shielding member 60 andthe other portion on the lower face 45 b side is covered by the lightshielding member 60.

Third Embodiment

FIG. 11 is a schematic top view of a light source 106 according to athird embodiment. The light source 106 differs from the light source 101of the first embodiment such that the light emission faces of the lightemitting elements in the light emission units do not have the same size.

The light source 106 includes a plurality of two-dimensionally arrangedlight emission units 56. The light emission units 56 include a pluralityof first light emission units 56A, a plurality of second light emissionunits 56B, a plurality of third light emission units 56C, and aplurality of fourth light emission units 56D.

As indicated by various hatching patterns in FIG. 11 , the lightemission faces 20 a of the light emitting elements in the first lightemission units 56A, the second light emission units 56B, the third lightemission units 56C, and the fourth light emission units 56D aredifferent. Assuming that the areas of the light emission faces 20 a forthe first light emission units 56A, the second light emission units 56B,the third light emission units 56C, and the fourth light emission units56D are Aa, Ab, Ac, Ad, respectively, they satisfy the relationship,Aa<Ab<Ac<Ad.

The distances from the center C of the light emission face of the lightsource 106 in which the light emission units 56 are arranged (i.e., theupper face of the light source 106) to the centers of the first lightemission units 56A, the second light emission units 56B, the third lightemission units 56C, and the fourth light emission units 56D in a topview are assumed to be ra, rb, rc, and rd, respectively. These distancesfor any two light emission units 56 selected in which the light emissionfaces 20 a have different areas satisfy the relationship, ra<rb<rc<rd.In other words, the larger the light emission face 20 a of the lightemitting element 20 of the light emission unit, the more distant it isfrom the center C.

Accordingly, the second light emission units 56B are more distant fromthe center C than the first light emission units 56A (ra<rb), and theareas of the light emission faces 20 a of the light emitting elements 20of the second light emission units 56B are larger than the areas of thelight emission faces 20 a of the light emitting elements 20 of the firstlight emission units 56A. The first light emission units 56A similarlysatisfy the relationship with the third light emission units 56C and thefourth light emission units 56D. The second light emission units 56Balso similarly satisfy the relationship with the third light emissionunits 56C and the fourth light emission units 56D. The third lightemission units 56C also similarly satisfy the relationship with thefourth light emission units 56D.

The light source 106 structured as above has higher luminance in theperipheral area than the central area of the light emission face 101 awhen all light emission units 56 are lit. Such light emissioncharacteristics can achieve more appropriate lighting when used incombination with a projection lens in a lighting device. The detailswill be explained in relation to a fourth embodiment.

Fourth Embodiment

An embodiment of a light source device will be explained. FIG. 12A is aschematic front view of a light source device 201, and FIG. 12B is aschematic cross-sectional view of the light source device 201 takenalong line 12B-12B in FIG. 12A.

The light source device 201 includes a lens 202 and a light source 203.In this embodiment, the light source device 201 further includes asubstrate 205 and a support 204. For the light source 203, a lightsource according to any of the embodiments described above can be used.For example, the light source 203 is the light source 106 of the thirdembodiment. The light source 203 is disposed on the substrate 205. Thesubstrate 205 provided with a drive circuit that can independently drivethe light emission units 56 of the light source 203 is electricallyconnected to each of the light emitting elements 20 in the lightemission units 57.

The support 204 retains the lens 202 at a predetermined distance fromthe light emission face 203 a of the light source 203. The lens 202, forexample, is a convex lens, and the optical axis of the lens 202 isaligned with the center of the light emission face 203 a.

The lens 202 is a projection optical system and expansively projects thelight from the light source 203. When the light emission units 57 arepartially driven, the light having the intensity and the irradiationrange corresponding to the light intensity or blinking resulting fromthe partial driving is projected through the lens 202.

The projected light has good emission characteristics during partialirradiation, as explained with reference to the first embodiment.Because the light exiting the light source 203 is expansively projectedby the lens 202, similar to an imaging optical system, the amount oflight decreases in the peripheral area. However, as explained withreference to the third embodiment, such a light amount decline islessened because the peripheral portion of the light emission face 203 ahas higher luminance than the central area. Accordingly, uniform lightwithout illuminance nonuniformity can illuminate an object.

Test Example

The luminance distribution of the light exiting a light source accordingto an embodiment was measured by simulation. The luminance of the lightsource having light emission units 51 arranged in four rows by fourcolumns shown in FIG. 2C as a test example was measured by simulation.FIG. 13A shows the luminance distribution of the light source of thetest example. As a comparative example, the luminance of a light sourcesimilar to the test example except that the light transmissive memberhas no lateral faces exposed from the light shielding member wasmeasured by simulation. FIG. 13B shows the luminance distribution of thelight source of the comparative example. In the light emission units 51of the test example, the thickness t1 of each first region R1 (FIG. 2C)was 60 μm, the thickness t2 of each second region R2 was 30 μm. Thelight emission units of the comparative example had no first regions R1,and the thickness of each light transmissive member was 30 μm. Thedistance between the lateral faces of the light transmissive members andbetween the lateral faces of the wavelength conversion members facingvia the light shielding member was 25 μm in both the test andcomparative examples. FIG. 13A and FIG. 13B each show the luminancedistribution when the four light emission units in the center were notlit, i.e., the 12 light emission units in the peripheral area were lit.In FIGS. 13A and 13B, the whiter the area, the higher the luminance is.

As is understood from FIGS. 13A and 13B, in the test example, there ishardly any region with reduced luminance between the lit light emissionunits in the peripheral area, whereas in the comparative example, thereare low luminance regions between the light emission units. In the testexample, the contrast between the lit area and the unlit area is high,whereas in the comparative example, the contrast between the lit andunlit areas is low. This shows that the light source of this example hasgood emission characteristics during partial irradiation.

Any of the light sources and light source devices according to thepresent invention can be used as a light emitting device in variousapplications. For example, it can be suitably used as a light emittingdevice for various lighting applications.

What is claimed is:
 1. A light source device comprising: a substrate;and a light source including a plurality of light emission unitsarranged two-dimensionally on the substrate, wherein the light emissionunits include a first light emission unit arranged at a center among thelight emission units, the first emission unit including a first lightemission element having a first light emission face, a plurality ofsecond light emission units surrounding the first light emission unit,the second light emission units including a plurality of second lightemission elements, respectively, the second light emission elementshaving a plurality of second light emission faces, respectively, and aplurality of third light emission units surrounding the second lightemission units, the third light emission units including a plurality ofthird light emission elements, respectively, the plurality of thirdlight emission elements having a plurality of third light emissionfaces, respectively, the first light emission face and the second lightemission faces all have the same areas, and the third light emissionfaces have different areas.
 2. The light source device according toclaim 1, wherein the third light emission units include four lightemission units arranged at four corners of a square or a rectangle, thefour light emission units including four light emission elements,respectively, the four light emission elements having four lightemission faces with the same areas, respectively.
 3. The light sourcedevice according to claim 1, wherein each of the light emission unitsincludes a light emitting element and a wavelength conversion member. 4.The light source device according to claim 3, wherein each of the lightemission units further includes a light transmissive member disposed onthe wavelength conversion member.
 5. The light source device accordingto claim 3, wherein the light source further includes a light shieldingmember continuously disposed between adjacent ones of the light emissionunits, the light shielding member covering a lateral face of the lightemitting element and a lateral face of the wavelength conversion memberin each of the light emission units, the light shielding membercollectively retaining the light emission units.
 6. The light sourcedevice according to claim 5, wherein each of the light emission unitsfurther includes a light transmissive member disposed on the wavelengthconversion member, and a lateral face of the light transmissive memberis at least partially exposed from the light shielding member.
 7. Thelight source device according to claim 1 further comprising a lensdisposed at a predetermined distance from the light source.
 8. The lightsource device according to claim 1, wherein an optical axis of the lensis aligned with a center of an upper face in the light source.
 9. Thelight source device according to claim 1, wherein a shape of the lightsource is a rectangle in a top view.
 10. The light source deviceaccording to claim 1, wherein each of the light emission units includesa light emission element having a light emission face, and the larger adistance of one of the light emission units from a center of an upperface in the light source is, the larger the light emission face of thelight emission element of the one of the light emission units is. 11.The light source device according to claim 1, wherein the light emissionunits further include a plurality of fourth light emission unitssurrounding the third light emission units.